It's very easy to manage PDFs, spreadsheets, Microsoft Word documents and so on through Wagtail's admin interface. What if you generated such documents on-the-fly, and wanted them to be available in the Documents section of the Admin interface? I was faced with such a situation, and this is how I did it ...

import os
from datetime import datetime
from django.core.files.base import File
from wagtail.documents.models import Document

def create_wagtail_document(f, title):
    """
    programmatically create a wagtail document which will
    automatically be available in the Documents section of wagtailadmin
    """
    doc_file = File(open(f, "rb"), name=os.path.basename(f))
    doc = Document(
        title=title,
        file=doc_file,
    )
    doc.save()

f = os.path.join("your_file")
today = datetime.now().strftime("%Y-%b-%d-%a")
now = datetime.now().strftime("%-I:%M%p")
doc_title = f"My awesome document created on {today} at {now}"
create_wagtail_document(f, doc_title)

The solution was inspired by Pieter Claerhout's approach in Programatically importing images in Wagtail.